There are two remaining issues:

1. Compile flags are no longer automatically detected. The user must
   manually specify the flags using the CSC_OPTIONS env var.
   E.g. export CSC_OPTIONS="-C -I/usr/include/SDL2 -L -lSDL2"

2. The libSDL-X.Y.Z+ "features" do not actually reflect the installed
   version of SDL. They always assume the installed SDL >= 2.0.4.